1. Field of the Invention
The present invention relates to an optical fiber ribbon for wiring of equipment and a connector-attached optical fiber ribbon for wiring of equipment.
2. Description of the Background Art
The optical fiber ribbon is made by arranging a plurality of coated optical fibers in parallel and covering them with a collective coating so as to make an integral ribbon-like form. Japanese Patent Application Publication No. 2003-95706 describes coated optical fibers contained in an optical fiber ribbon. The coated optical fiber is such that the outer circumferential surface of a glass fiber is coated with two layers made of ultraviolet curable resin: an inner fiber coating layer and an outer fiber coating layer. The inner fiber coating layer has Young's modulus of about 1.2 MPa, and the outer fiber coating layer has Young's modulus of about 700 to 750 MPa, and the outer fiber coating layer is harder than the inner fiber coating layer. In this optical fiber ribbon, the glass fiber can be exposed by removing the inner fiber coating layer and the outer fiber coating layer together with the collective coating. When a coated optical fiber is attached to a connector, generally the glass fiber is bared to be fixed to the connector.
Japanese Patent Application Publication No. H 2-151821 discloses an optical fiber that is coated with two layers: an inner fiber coating layer made of acrylate fluoride and an outer fiber coating layer made of silicone resin. This optical fiber can be fixed to a connector in the condition where the outer fiber coating layer only is removed while the inner fiber coating layer remains as it is. In this manner, it is possible to prevent the glass fiber from being damaged, and hence the degradation of the transmission characteristics and mechanical strength can be avoided.
However, in the case of an optical fiber ribbon, in which such a kind of coated optical fibers as disclosed by Japanese Patent Application Publication No. H 2-151821 are further covered with a collective coating, the attempt to remove the outer fiber coating layer together the collective coating will often result in failure: it is difficult to pull out the outer fiber coating layer in a clean layer condition, that is, the residues of the silicone resin might be left on the inner fiber coating layer. This is because the silicone resin is fragile.